Hogwarts Hearts
by chamberpotter91
Summary: What if the world of Hogwarts was part of a larger universe? The heart of Hogwarts is infected with darkness, and only The Boy Who Lived and the Keyblade Wielder can save it - with Luna Lovegood along for the ride! Kingdom Hearts/Harry Potter crossover
1. Chapter 1

Harry Potter was spending Christmas at Hogwarts, like every single other holiday, because naturally, the Dursleys would never take him. He stared out the window into the snowy courtyard, lost in thought, when suddenly he saw something odd. There was a black patch of space appearing in the midst of the snowy Hogwarts courtyard, like someone had spilt black ink on pure white paper. As Harry stared, the black spot grew bigger and bigger until it became doorway-sized, and out stepped the strangest people Harry had ever seen.

There was a boy around Harry's age, with spiky dark hair forming bangs over his striking cerulean eyes and wearing a strange black costume, festooned with brightly colored buckles and zips all over the place. He was followed by some strange creatures Harry had never seen before, not even in his Defence Against the Dark Arts classes. The first looked like a giant white duck, but wearing a strange blue costume resembling a sailor's uniform and wielding a strange looking staff, while the other was a somewhat canine looking creature with a green shirt and yellow pants, holding a shield. As soon as the trio appeared in the snow, they immediately drew together, forming a tightknit group with their backs to each other, eyes warily scanning the Hogwarts courtyard.

Harry leaned in closer to the window, wondering at the strange behaviour of these strangers, when suddenly the courtyard erupted in with strange black creatures that almost looked like mini Dementors. Harry gave a cry of surprise, but the strangers appeared to be expecting this, and began fighting them with strange weapons: a staff, a shield and a strange sword in the shape of a key. It took Harry milliseconds to figure out what he had to do. He quickly grabbed his wand and rushed out of Gryffindor tower, making for the courtyard.

Harry left Gryffindor Tower and made his way out of the Fat Lady's portrait and quickly down the castle towards the entrance. He ran lightly down the empty hallways and was going down the stairs when-

"Ooof"

Harry bumped into someone as he was rushing down the stairs towards the Hogwarts courtyard. Looking down, he saw Luna Lovegood sprawled out on the stone landing, her blonde hair in disarray.

"I'm sorry Luna, I was just in a hurry and-"

"That's fine Harry." Luna got up and dusted herself off. "Is it the nargles?"

"What? No, no..."

Luna turned to go, then suddenly Harry had a brainwave.

"Wait, Luna. It's not nargles, but it's definitely not something I've seen before. Get your wand out too. You'll need your DA training for this. Follow me to the courtyard."

Luna nodded her head, her radish earrings swaying wildly under her hair. She got her wand out from its holster and followed Harry down to the courtyard.

The strange boy was there, and there seemed to be more of the strange black creatures. Harry heard Luna gasp behind him. Turning to look at her, he saw that her eyes were alight with a strange enthusiasm he'd never seen from her.

"Heartless!" Luna said. "Quick, call your Patronus!"

Harry had no time to think, and instead just shouted "Expecto patronum!"

He saw the familiar silver light come from his wand, with the silvery spectral stag chasing the black figures away from the strangers and destroying them.

And it looked like they'd reached there not a moment too soon.


	2. Chapter 2

The strange boy was lying prone on the flagstones of the Hogwarts central courtyard. Around him, the black figures disappeared into thin air. The strange creatures he had arrived with were standing over him, the tall one wringing its (his?) hands in despair while the shorter one poured a potion into his mouth. To the relief of Harry and Luna, the boy sat up, shook his head and stood.

"Gawrsh, thanks stranger!" The tall creature said. Harry was taken aback. It could speak?

"Of course," Luna said. "I'm glad we could help you."

Harry glanced sideways at Luna, who was seemingly unperturbed by these strange beings.

"Hi, I'm Sora." The dark haired boy said. "This is my friend Goofy", he said, pointing to the larger of the strange duo and pointing to the smaller figure he said "and this is Donald."

"Harry Potter. And this is my friend Luna Lovegood," said Harry. He creased his brow and asked "What were those things?"

"Heartless," Luna piped up suddenly.

"Sorry?"

"Heartless are dark creatures who have lost their hearts, and try to steal the hearts of others." Luna said. "My dad saw one. He says that dark wizards can also create them."

"They sound like Dementors," Harry said, his eyes hardening.

Luna nodded. "Yes, that's why the Patronus charm works so well on them. Otherwise, Incendio is also good."

Sora cleared his throat, and Luna took a close look at him for the first time. He was taller than her, and around the same age. His dark brown hair was as unruly as Harry's and his blue eyes were just as striking, and Luna felt almost protective of him. But looking at his companions, she realised she didn't have to be - the way they stood near him showed that they'd been through so much together and were willing to fight to the death for each other. Luna looked over at Harry and wondered if they'd ever be like that.

"Would there be any reason why the Heartless are appearing in the world?" Donald asked. "Any great evil, or big changes?"

Harry laughed bitterly. "Well there is that little matter of Lord Voldemort. Now that I think about it he'd be exactly the sort of Dark wizard to use the Heartless on his side. It's the first time I've seen them here in Hogwarts though."

"That's a very bad sign," Sora said. "We need to find and stamp them out at the source before your world gets overrun."

"Agreed," said Harry.

Some sort of silent agreement passed between the two boys. An alliance against evil had been forged.

"Any ideas on where they'd be?" Sora asked.

"I guess we can start in the castle." Harry said. "Come with me."


End file.
